Pressure switch



July 12, 1966' c. A. SCHAD PRESSURE SWITCH Filed Sept. 25, 1965 'll lllllL lHlllllIli FIGJ INVENTOR CHARLES A .SCHAD BY jg a ATTORNEYS United States Patent 3,260,816 PRESSURE SWITCH Charles A. Schad, Tulsa, Okla., assiguor to Murdock Associates, Inc., Tulsa, Okla, a corporation of Oklahoma Filed Sept. 25, 1963, Ser. No. 311,407 6 Claims. (Cl. 200-83) This invention relates to a pressure switch. More particularly, this invention relates to a device adapted for use as a head pressure switch. Still more particularly, this invention relates to the improvements in a head pressure switch including visual indicating means in conjunction with the switch mechanism.

In modern industry pressure switches are used for many purposes and applications. A typical use is for switching pumps and valves in response to the level of liquid in a vessel. The liquid level is indicated by the static pressure exerted from the liquid in the vessel. Many types of switches are available for actuation by liquid level in tanks and vessels however, a head pressure switch has several advantages which have made them highly popular in industry, particularly in the oil industry. One advantage of the head pressure switch is that the switch mechanism can be located at a distance from the vessel in which the height of fluid is being detected. Another advantage is economy and, in contrast with float switches and other level detecting means, the liquid level at which the switch is actuated can be easily varied.

A disadvantage which all known types of pressure switches have is the problem of calibration. A float switch or other device mounted on or within a vessel to detect the height of liquid in the vessel is readily calibrated by the actual fluid height. A totally diflerent and vastly more difficult problem arises in calibration of a head pressure switch remotely located from the vessel in which the liquid level is being detected. Another problem, ancillary to calibration, is that known types of head pressure switches have no means of indicating relative height of fluid in the vessel. This is a decided disadvantage to the operators of industrial equipment since fre quently the operators need to know the general level of fluid in the vessel. This disadvantage in known types of pressure switches is overcome in the below described invention.

Accordingly, it is an object of this invention to provide an improved pressure switch and particularly a pressure switch adapted for use as a head pressure switch actuated upon changing heights of fluid in a vessel.

Another object of this invention is to provide a liquid level switch including the provision of a visual level indicating means.

Another object of this invention is to provide a liquid level switch including dampening fluid to improve the performance of the switch and including novel means of utilizing the dampening fluid in a manner to provide a visual indication of the pressure exerted on the switch.

Another object of this invention is to provide a pressure switch including the provision of a multiplicity of different switches actuated by-diflerent fluid pressures.

Another object of this invention is to provide a pressure switch having improved performance, serviceability, applicability, and economy of construction.

These and other objects and a better understanding of the invention may be had by referring to the following description and claims taken in conjunction with the attached drawings in which:

FIGURE 1 is a front external view of an embodiment of the pressure switch of this invention.

FIGURE 2 is a cross-sectional view taken along 2-2 of FIGURE 1 showing the details of construction of the pressure switch of this invention.

Patented July 12, 1966 FIGURE 3 is a cross-sectional view taken along line 3-3 of FIGURE 2 showing further details of construction of the switch of this invention.

FIGURE 4 is a cross-sectional view taken along the line 4-4 of FIGURE 2 showing details of the arrangement of the switch actuating .portion of the invention.

This invention may be described as a pressure switch. More particularly, but not by way of limitation, the invention may be described as a pressure switch comprising a container body divided by a partition into an upper measuring chamber and a lower chamber, a diaphragm dividing said lower chamber into a lower pressure receiving chamber and an upper dampening chamber, said body having a pressure passage opening communicating with said pressure receiving chamber, said partition wall having a shaft receiving opening and a dampening fluid opening therein communicating said dampening chamber with said measuring chamber, said measuring chamber having a visual level indicating opening therein, a switch means supported to said upper chamber, a shaft having the lower end thereof ailixedto said diaphragm, said shaft extending slidably in said shaft receiving opening, the upper end of said shaft extending to contact said switch means and to actuate said switch means upon displacement of said diaphragm, spring means constraining said diaphragm to maintain minimum volume in said pressure receiving chamber against the force of pressure exerted into said pressure receiving chamber through said pressure passage opening, dampening fluid filling said dampening chamber, and a transparent liquid level indicating member closing said visual level indicating opening of said upper chamber.

Referring now to the drawings and first to FIGURE 1, the pressure switch of this invention is generally indicated by the numeral 10. The switch 10 consists essentially of a body 12 preferably of elongated hollow construction, having an integrally formed lower cylindrical portion 14. A pressure receiving portion 16, cylindrical in construction and adapted to engage, such as by means of bolts 18, the cylindrical portion 14 is provided. An integral pressure connecting nipple 20 is provided as means for coupling the switch to a pressure line.

Aflixed at the upper end of the body portion 12 is a switch housing, covered by a removable closure 22. The switch housing is shown supported to body 12 by means of bolts 24.

One of the important novel features of this invention is the provision of a visual pressure indicating means in conjunction with the switch function of the device. A transparent level indicating window 26 is provided cover ing an opening in body 12. A flange 28 holds window 26 in place, the flange in turn being supported to body 12 by means of screws 30.

Referring now to FIGURE 2 the details of construc tion of the invention are best shown. The switch body 12 may be said to be divided into an upper measuring chamber 32 and a lower chamber 34 by means of a partition wall 35. The lower chamber 34 is in turn divided into an upper dampening chamber 34A and a lower .pressure receiving chamber 34B by a diaphragm 36. Pressure entering the switch through pressure connecting nipple 20 acts on the diaphragm in a manner to be described subsequently.

Aflixed to diaphragm 36 is a shaft 38 extending upwardly through an opening 40 in the partition wall 35. In the preferred embodiment the opening 40 is of a size to slidably receive shaft 38 but to substantially prevent flow of fluid therethrough. Shaft 38 extends upwardly within the upper measuring chamber 32 and into the interior of switch housing 42. A threaded opening 44 in the upper end of body 12 receives a tubular externally threaded tension adjusting nut member 46. The tubular opening 48 in the nut member permits shaft 38 to freely slide therein.

A compression spring 50 extends between the lower end of tension adjusting nut 46 and a washer 52. The washer 52 in turn is supported against an enlarged shoulder portion 54 of the shaft 38 so that spring 50 urges the shaft 38 and diaphragm 36 downwardly against the force of any pressure exerted through the pressure connecting nipple 20.

To provide dampening and thereby prevent sudden actuations of diaphragm 36 the upper cavity 34A of the lower chamber is filled with a dampening fluid 53, such as light oil or a silicon liquid. To provide means of controlling the rate of flow of the dampening liquid 53 out of chamber 34A as pressure urges the diaphragm 36 upwardly, a dampening passage 56 is provided communicating between the dampening chamber 34A and the upper measuring chamber 32. A throttle screw 58 is provided as a means of controlling the rate of flow of fluid between the chambers 34A and the measuring chamber 32.

To permit the escape of air out of measuring chamber as diaphragm 36 rises, forcing liquid therein, an air passage 60 may be provided. A filter (not shown) may be placed in the air passage 6% if desired.

FIGURE 3 shows the cross-sectional configuration of body member 12 having the shaft 38 therein, it being understood that the geometrical arrangement of the various components of the invention may be varied in a number of ways without departing from the essence of the invention.

As the shaft 33 is urged upwardly by pressuring diaphragm 36 a switch bar 62 aflixed to the upper end of shaft 38 within the switch housing 42 which is moved upwardly. An important novel element of this invention is the provision of means for the actuation of a multiplicity of switches by the effect of the movement of diaphram 36. Located within the switch housing 42 and above switch bar 62 are a multiplicity of micro-switches 64, each having a downwardly extending longitudinally displaceable plunger 65. Three switches designated 64A through 64C are shown, it being understood that there may be a lesser or fewer number within the purview of the invention. Each of the micro-switches 64 is individually adjustable by means of screws 66 retaining their supporting brackets 68. Switch block 62 is provided with a switch actuating bolt for each of the micro switches, designated 70A through 70C.

Referring to FIGURE 4 the details of the arrangement of the multiple switch actuating portion of the invention are best shown. Each of the actuating bolts 70 is slidably supported within an opening 72 in the switch block 62. Nuts 74 are provided at the lower end of the bolts 70 as a means of regulating the height the head of the bolts extend above the switch block 62. A spring 76 urges each of the actuating bolts 79 upwardly in a resilient manner, and permits over-travel of the switch block; that is, the switch block 62 is free to move upwardly even after a switch has been contacted and actuated.

A conductor opening 73 is provided in switch housing 42 as a means whereby conductors may pass to connect to the switches 64A, 64B, and 64C.

Operation The improvement of this invention providing an indicating gage in conjunction with a pressure switch will be first described. When pressure is applied through pressure connecting nipple 40, such as the hydrostatic pressure of a vessel filled with a liquid, the diaphragm 36 is moved upwardly. This upward movement forces dampening fluid 53 within chamber 34A through the dampening passage 56 into upper measuring chamber 32. Thus the amount of fluid within the upper measuring chamber 32 is directly related to the displacement of diaphragm 36 which due to the tension impressed by spring 50, is related to the pressure applied below the diaphragm. By visual observation of the transparent window 26 in the front of the switch the liquid level within upper measuring chamber 32 is readily indicated. Calibration marks shown on the window 26 indicate the pressure exerted on the switch. When the switch of this invention is used to control the level of fluid in a vessel by detection of a hydrostatic pressure of the vessel fluid, markings on the window 26 can be arranged so that the level of dampening fluid within measuring chamber 32 indicates directly the heights of fluid in the vessel. In this manner, by a unique arrangement of the provision of a measuring chamber and a window in conjunction with a pressure switch means, there is provided a gage or level indicator in conjunction with a pressure switch at very little additional expense. The use of dampening fluid 53 has as its primary purpose the prevention of erratic fluctuations of diaphragm 36 so that the switch functions by the average or mean pressure applied to it. This invention makes use of this dampening fluid in a novel way to provide visual monitoring of the pressure to which the switch is subjected.

A second important novel element of the invention is the provision of means of actuation of a multiplicity of switches by the movement of switch rod 38. In a typical industrial application wherein the switch of this invention is utilized to control the level of fluid in a vessel, several operations may be frequently required, such as: (A) a function to be actuated when the vessel is empty, such as closing a vessel discharge valve; (B) a function to be actuated, such as to turn on a pump or open a valve, when the vessel is filled to a predetermined height; and (C) a function when an emergency condition exists wherein the vessel is filled beyond the predetermined height at which emptying or other action is required. As an example, switch 64A may be considered a low stop switch; that is, a switch which when opened will stop a pump, close a valve, or so forth. Switch 648 may be used as a run start switch; that is, a switch actuated when the liquid level in the vessel to which the switch of this invention is connected reaches a predetermined height wherein it is desired to perform some functions, such as start a pump or open a valve. The third switch 64C may be typically a high alarm switch actuated to initiate an alarm condition such as an audible alarm, or automatic shut down procedure, when the liquid level in the vessel has risen to a height exceeding the maximum acceptable height desired. Thus it can be seen that by the provision of a multiplicity of actuating bolts 70 each set at a different height the three switches 64A, 64B, and 64C can be caused to be actuated as a result of different pressures to which the switch is subjected thereby adapting the switch to many industrial uses.

An important area of usefulness of the improvement of this switch include means whereby the actuation of switches 64A, 64B and 64C can be more easily calibrated. A typical pressure switch has no means available for indicating the pressure to which the switch is subjected so that adjusting the switch for proper calibration is difficult. By the novel provisions of this invention, including the provision of the visual indicating window 26, the pressure to which the switch is subjected is easily indicated at the switch itself.

Although this invention has been described with a certain degree of particularity it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure.

What is claimed:

1. A pressure switch comprising:

a body member divided by a partition wall into an upper measuring chamber and a lower chamber, said upper measuring chamber having a level indicating opening therein;

a diaphragm dividing said lower chamber into a lower pressure receiving chamber and an upper dampening chamber, said body member having a pressure passage opening at the lower end thereof communicating with said pressure receiving chamber, said partition wall having a shaft receiving opening and a dampening fluid passageway therein communicating said dampening chamber with said measuring chamber;

a switch means supported to said upper chamber;

a shaft having the lower end thereof aflixed to said dia phragm, said shaft extending slidably through said shaft receiving opening in said partition wall, the upper end of said shaft extending to contact said switch means and to actuate said switch means upon displacement of said diaphragm;

spring means downwardly constraining said diaphragm;

dampening fluid filling said dampening chamber and said dampening fluid passageway, said dampening fluid forced upwardly from said dampening chamber through said fluid passageway and into said measuring chamber as said diaphragm is moved upwardly by pressure in said lower pressure receiving chamber;

and a transparent liquid level indicating panel closing said level indicating opening of said upper chamber.

2. A pressure switch according to claim 1 including an orifice means in said dampening fluid passageway.

3. A pressure switch according to claim 1 including a tension adjusting means adjustably varying the tension of said spring means.

4. A pressure switch according to claim 1 wherein said switch means includes a micro-switch means having an actuating plunger extending therefrom, and including:

a switch bar supported to said shaft at the upper end thereof, said switch bar having an opening therein;

an actuating bolt slidably supported in said switch bar opening, the upper end of said actuating bolt disposed to engage and depress said actuating plunger of said micro-switch upon upward movement of said shaft;

spring means resiliently biasing said actuating bolt in the upward direction; and

a calibrating nut threadably engaging said actuating bolt below said switch bar.

5. A pressure switch according to claim 1 wherein said switch means includes a multiplicity of micro-switch means each having an actuating plunger extending therefrom, each of said micro-switches supported to said upper chamber in substantially horizontally spaced relationship;

a switch bar supported to said shaft at the upper end thereof, said switch bar having openings therein in registry with each of said micro-switches;

an actuating bolt slidably supported in said switch bar opening in registry with each of said micro-switches, the upper end of each said actuating bolts disposed to engage and depress the actuating plunger of one of said micro-switches upon upward movement of said shaft;

individual spring means resiliently biasing each of said actuating bolts in the upward direction; and

a calibrating nut threadably engaging each of said actuating bolts below said switch bar.

6. A pressure switch according to claim 1 including a switch housing affixed to said container body at the upper end thereof, said housing having a shaft receiving opening therein through which the upper end of said shaft slidably I extends, and wherein said switch means is supported in said switch housing.

References Cited by the Examiner UNITED STATES PATENTS 2,418,536 4/1947 Wood 20083.4 2,419,685 4/1947 Lesli 20083.4 2,583,397 1/1952 Strysko. 3,046,784 7/ 1962 Vicik et al 73-300 3,097,276 7/ 1963 Ellett ZOO-83.51

5 BERNARD A. GILHEANY, Primary Examiner.

G. MAIER, Assistant Examiner. 

1. A PRESSURE SWITCH COMPRISING: A BODY MEMBER DIVIDED BY A PARTITION WALL INTO AN UPPER MEASURING CHAMBER AND A LOWER CHAMBER, SAID UPPER MEASURING CHAMBER HAVING A LEVEL INDICATING OPENING THEREIN; A DIAPHRAG, DIVIDING SAID LOWER CHAMBER INTO A LOWER PRESSURE RECEIVING CHAMBER AND AN UPPER DAMPENING CHAMBER, SAID BODY MEMBER HAVING A PRESSURE PASSAGE OPENING AT THE LOWER END THEREOF COMMUNICATING WITH SAID PRESSURE RECEIVING CHAMBER, SAID PARTITION WALL HAVING A SHAFT RECEIVING OPENING AND A DAMPENING FLUID PASSAGEWAY THEREIN COMMUNICATING SAID DAMPENING CHAMBER WITH SAID MEASURING CHAMBER; A SWITCH MEANS SUPPORT TO SAID UPPER CHAMBE; A SHAFT HAVING THE LOWER END THEREOF AFFIXED TO SAID DIA- 